function add (num1, num2) {
    return num1 + num2;
}

function subtraction (num1, num2) {
    return num1 - num2;
}

function multiply (num1, num2) {
    return num1 * num2;
}

function divide (num1, num2) {
    return num1 / num2;
}

module.exports.add = add;
module.exports.subtraction = subtraction;
module.exports.multiply = multiply;
module.exports.divide = divide;